The rapid and massive degeneration of photoreceptors in
retinal degeneration might have a dramatic negative effect on
retinal circuits downstream of photoreceptors. However, the impact of photoreceptor loss on the morphology and function of retinal ganglion cells (RGCs) is not fully understood, precluding the rational design of therapeutic interventions that can reverse the progressive loss of
retinal function. The present study investigated the morphological changes in several identified RGCs in the
retinal degeneration rd1 mouse model of
retinitis pigmentosa (RP), using a combination of viral transfection, microinjection of
neurobiotin and confocal microscopy. Individual RGCs were visualized with a high degree of detail using an adeno-associated virus (AAV) vector carrying the gene for
enhanced green fluorescent protein (EGFP), allowed for large-scale surveys of the morphology of RGCs over a wide age range. Interestingly, we found that the RGCs of nine different types we encountered were especially resistant to photoreceptor degeneration, and retained their fine dendritic geometry well beyond the complete death of photoreceptors. In addition, the RGC-specific markers revealed a remarkable degree of stability in both morphology and numbers of two identified types of RGCs for up to 18 months of age. Collectively, our data suggest that
ganglion cells, the only output cells of the retina, are well preserved morphologically, indicating the
ganglion cell population might be an attractive target for treating vision loss.